1. Field of the Invention
This invention relates to an absorbent composition useful for removing sulfur-containing compounds from a variety of fluids, and particularly from liquid and gaseous hydrocarbons and carbon dioxide. The absorbent primarily comprises ferrous carbonate, desirably obtained from the mineral siderite, and is used for removing hydrogen sulfide, mercaptans, dimethyl disulfide and other sulfur-containing compounds from gaseous hydrocarbon streams, light liquid hydrocarbon streams such as natural gas liquids (“NGL”), crude oil, acid-gas mixtures, carbon dioxide gas and liquid, anaerobic gas, landfill gas, geothermal gas, and the like. Methods for making and using the absorbent for sulfur removal are also disclosed.
2. Description of Related Art
Because of the noxious, toxic and corrosive nature of sulfur-containing compounds, many different products and methods have previously been disclosed for use in removing such compounds from liquid and gaseous streams. One such commercially available product is SULFATREAT® brand particulate reactant that is said to be useful for removing hydrogen sulfide and other sulfur contaminants from gases and liquids including, for example, hydrocarbon fuels and geothermal steam for sale to producers of natural gas and the like. SULFATREAT® is a federally registered trademark of M-I L.L.C. of Houston, Tex. and, in stylized form, of Gas Sweetener Associates, Inc. of Chesterfield, Mo. The SULFATREAT® material has a proprietary formulation but is believed to comprise primarily ferric oxide particles having a high surface area. Iron sponge is another commercially available material composed of ferric oxide distributed on wood chips that is being used for sulfur removal in industrial processes.
Other iron-containing compositions and methods for removing sulfur from gas and liquid streams are disclosed, for example, in U.S. Pat. Nos. 4,008,775; 4,344,842; 4,366,131; 4,476,027; 4,705,638; 4,956,160 and 5,948,269. U.S. Pat. No. 5,948,269, for example, discloses a process for the removal of dissolved hydrogen sulfide and other malodorous compounds from aqueous liquid or sludge waste systems such as found in sewage collection and treatment works; industrial and commercial waste systems, natural and manmade polluted impoundments or waterways, and septic systems, by use of “alkaline iron.” As used in U.S. Pat. No. 5,948,269, “alkaline iron” refers to an alkali with a variety of iron compounds including ferrous carbonate.